EP0623643B1 - Polymeric multinary azanes, process for their preparation and their use - Google Patents

Abstract

The present invention relates to polymeric multinary azanes built up from units of the formula [E(NR<1>R<2>)a(NR<3>)b/2], in which E = B, Al, Ga, In, Si, Ge, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, or W, and R<1>, R<2> and R<3> = H, C1-C6-alkyl, vinyl or phenyl, to a process for the preparation of these polymers, and to their use as precursor compounds for high-performance ceramic materials.

Description

The present invention relates to polymeric multinary azanes which are composed of structural units of the general formula [E (NR ¹ R ² ) _a (NR ³ ) _{b / 2} ], in which E = B, Al, Ga, In, Si, Ge, Ti , Zr, Hf, V, Nb, Ta, Cr, Mo, W and R ¹ , R ² , R ³ = H, C ₁ -C ₆ alkyl, vinyl, phenyl, process for the preparation of these polymers and their use as a precursor for ceramic high-performance materials.

The sol-gel process has outstanding results in the field of oxidic systems Gaining importance for the production of precursors for glasses and ceramics Materials. It enables the particle size and morphology to be controlled Products obtained are characterized by homogeneous element distribution, high Purity and uniform particle size. It seems desirable this Process also for the synthesis of nitridic or carbonitridic systems use that for some time increasingly for use as ceramic High-performance materials are examined.

So far, the options are through a sol-gel process for oxidic Systems analogous process polymeric precursor compounds for ceramic To produce nitrides and carbonitrides, still little studied.

According to Can.J.Chem 41 (1963) 134, polymeric titaniumazanes are obtained by reacting Ti (NR ₂ ) ₄ with primary amines. From J.Am.Ceram.Soc. 71 (1988) 78 shows the ammonolysis of dialkylamides of titanium, niobium or zirconium and the pyrolysis of the polymeric metallazanes obtained to give the corresponding binary nitrides. Syntheses of polymeric azanes containing more than one transition metal have so far not been disclosed
The synthesis of polymeric multinary azanes has so far only been described for the Si-BN system:

According to EP-A-389 084 and EP-A-0 424 082, soluble polyborosilazanes by reacting polysilazanes or polyorganosilanes with organic boron Receive connections. DE-A 4107108 discloses the production of oligo or polyborosilazanes by polymerizing heterometallic monomers with Ammonia or alkylamines. However, these methods do not allow the To vary the stoichiometry of the products as desired; the synthesis of the aforementioned heterometallic monomers is also associated with considerable effort.

The object of the invention is to provide novel, simple and high Yield representable polymeric multinary azanes with adjustable Stoichiometry, which have a homogeneous element distribution, and one Process for the preparation of multinary nitridic and carbonitridic Ceramics made from these polymers.

The requirements are met by the following polymers which are the subject of this invention. These are polymeric multinary azanes which are composed of structural units of the general formula [E (NR ¹ R ² ) _a (NR ³ ) _{b / 2} ], in which E = B, Al, Ga, In, Si, Ge, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and R ¹ , R ² , R ³ = H, C ₁ -C ₆ alkyl, vinyl, phenyl, characterized in that at least two of the with the exception of the combinations Si-B and Si-Al, and each atom E is coordinated by three to six nitrogen atoms, where 0≤a≤6, 1≤b≤6, 3≤ (a + b) ≤6 and a and b mean integers.

In a preferred embodiment, the polymers according to the invention are multinary azanes characterized in that the elements E in homogeneous Distribution available. In a particularly preferred embodiment, the Element distribution uniform up to at least a resolution of 0.5µm.

In a preferred embodiment, the inventive ones stand out polymeric multinary azanes with a low chloride content. He is preferably <100 ppm, in a particularly preferred embodiment <20 ppm. The chloride content of the polymers is determined by the Chloride content of the element amides used in the production. Height Chloride levels in the polymers have a negative effect on further processing out. In particular, corrosion occurs to an increased extent during the pyrolysis of the polymers. in the ceramic material cause high chloride content poorer sintering properties and a reduced final density.

This invention further relates to processes for the preparation of the polymeric multinary azanes according to the invention.

Mixtures of elementamides of the composition E (NR ¹ R ² ) _n , where 3 ≦ n ≦ 6, E = B, Al, Ga, In, Si, Ge, Ti, Zr, Hf, V , Nb, Ta, Cr, Mo, W and R ¹ = H, C ₁ -C ₆ alkyl, vinyl, phenyl, R ² = C ₁ -C ₆ alkyl, vinyl, phenyl can mean, in bulk or in one aprotic organic solvents are polymerized with ammonia or primary amines.

In a preferred embodiment, the reaction is carried out at temperatures between -80 ° C and 200 ° C either in bulk or in an aprotic organic solvent, which can be a C ₅ -C ₈ alkane, an acyclic or cyclic ether or an alkyl aromatic , where the concentration of the amides is> 0.01m.

The number and the mixing ratio of the amides used can be as desired be selected so that any desired stoichiometry in terms of the product Elements E can be set.

The reactivity of the starting materials can be changed in a targeted manner by varying the radicals R ¹ and R ² and selecting a solvent with appropriate donor properties. The ammonolysis rates of the amides can be matched and a homogeneous distribution of the elements E in the polymer can thereby be achieved. Furthermore, the polymerization rate can be controlled, which makes it easier to control the process conditions during production. In addition, the properties of the polymers according to the invention can be optimized with regard to further processing. In a preferred embodiment, R ¹ and R ^{2 are} C ₁ -C ₄ alkanes.

The viscosity of the solutions can be determined via the concentration of the polymer Solution vary widely and allows optimization of that for the further processing required properties.

A control of the Degree of crosslinking and the molecular weights of the polymers according to the invention possible. Viscous oils can be obtained at low temperatures, at higher temperatures Temperatures create solids.

To produce powders, the solvent is preferably reduced Pressure removed. Other common ones are also suitable Dry process.

The invention also relates to the use of the polymeric multinary azanes according to the invention for the production of multinary nitrides or carbonitrides by pyrolysis in an atmosphere containing noble gas, N ₂ , NH ₃ or primary amines at from 400 to 2000 ° C.

In a preferred embodiment, the polymers are pyrolyzed in the NH ₃ stream at temperatures of 400-1000 ° C. for the synthesis of purely nitridic material and then calcined to remove the remaining hydrogen at temperatures between 1400-2000 ° C. in an N ₂ or argon atmosphere. For the synthesis of carbonitridic material, both steps are carried out under N ₂ or Ar.

The invention also relates to the use of the polymeric multinary azanes according to the invention for the production of ceramic moldings, foils, fibers or coatings by pyrolysis in an inert gas, N ₂ , NH ₃ or primary amine-containing atmosphere at temperatures of 400 to 2000 ° C.

The choice of the polymerization agent enables the properties to be controlled of the polymers according to the invention. Polymerize with ammonia insoluble thermosets, polymerization with primary amines leads to the common organic solvents soluble thermoplastics, which directly in Solution or as a melt subjected to various shaping processes can be e.g. Casting, spinning into fibers, drawing of foils, Production of coatings by various coating processes such as Dip (coating) or centrifugal coating (spin coating).

The invention is explained by way of example below, without any Restriction can be seen.

Example 1: Representation of a polytitanosilazane with a Si / Ti ratio of 1: 1 Reaction equation:

Carrying out the experiment:

A solution of 8.88 g (0.06 mol) Si (NHCH ₃ ) ₄ and 13.56 g (0.06 mol) Ti (N (CH ₃ ) ₂ ) ₄ in 500 ml pentane was added at -78 ° C with stirring 50 ml NH ₃ . The reaction mixture was allowed to warm to room temperature over 12 h. The solvent was distilled off under reduced pressure. 12.4 g of yellow polytitanosilazane were obtained. Analytical data of the polymer:
Infrared Spectroscopy [cm ^-1 ]: 3340 (m); 2920, 2810 (s); 2100 (w); 1550 (w), 1380 (m); 1100 (s); 920 (ss); 550 (m, vb). Powder diffractometry: amorphous. Energy-dispersive X-ray analysis: Homogeneous polymer, Si: Ti ratio = 1: 1.

5 g of the polymer were pyrolyzed in a stream of ammonia at 1000 ° C. for 12 hours. 3.1 g of a black glossy amorphous powder were obtained, corresponding to a ceramic yield of 62%. Analytical data of the pyrolysis product:
Infrared Spectroscopy [cm ^-1 ]: 3400 (w); 950 (s, b); 470 (m, b). Powder diffractometry: amorphous. Energy-dispersed X-ray analysis: Homogeneous element distribution at least up to the resolution limit of 0.5 µm, ratio Si: Ti = 1: 1

Example 2: Representation of a polytitanosilazane with a Si / Ti ratio of 2: 1 Reaction equation:

Carrying out the experiment:

30 ml of NH _{3 were} added to a solution of 6 g (0.04 mol) of Si (NHCH ₃ ) ₄ and 4.5 g (0.02 mol) of Ti (N (CH ₃ ) ₂ ) ₄ in 300 ml of tetrahydrofuran at -78 ° C. with stirring. The reaction mixture was allowed to warm to room temperature over 12 h. The solvent was distilled off under reduced pressure. 7.1 g of yellow polytitanosilazane were obtained. Analytical data of the polymer:
Infrared Spectroscopy [cm ^-1 ]: 3400 (s); 2920, 2890 (m); 1620 (w); 1460, 1385 (m); 1185 (m); 1040 (ss); 450 (m). Powder diffractometry: amorphous. Energy-dispersed X-ray analysis: homogeneous polymer, Si: Ti ratio = 2: 1.

5 g of the polymer were pyrolyzed in a stream of ammonia at 1000 ° C. for 12 hours. 2.75 g of a black glossy amorphous powder were obtained, corresponding to a ceramic yield of 55%. Analytical data of the pyrolysis product:
Infrared Spectroscopy [cm ^-1 ]: 3400 (w); 950 (ss); 460 (m, b). Powder diffractometry: amorphous. Energy-dispersed X-ray analysis: Homogeneous element distribution at least up to the resolution limit of 0.5 µm, ratio Si: Ti = 2: 1

Example 3: Representation of a polyzirconosilazane with an Si / Zr ratio of 1: 1 Reaction equation:

Carrying out the experiment:

50 ml of NH _{3 were} added to a solution of 7.4 g (0.05 mol) of Si (NHCH ₃ ) ₄ in 400 ml of pentane at -78 ° C. with stirring. After 5 minutes, 12.8 g (0.05 mol) of Zr (N (CH ₃ ) ₂ ) ₄ in 100 ml of pentane were added. The reaction mixture was allowed to warm to room temperature over 12 h and stir for a further 4 h. The solvent was distilled off under reduced pressure. 11.4 g of yellow polyzirconosilazane were obtained. Analytical data of the polymer:
Infrared Spectroscopy [cm ^-1 ]: 3350 (s); 2890, 2800 (s); 1470 (w), 1370 (m); 1260 (m); 1100 (ss); 800 (s); 520 (m); 470 (m).
Powder diffractometry: amorphous. Energy-dispersed X-ray analysis: homogeneous polymer, ratio Si: Zr = 1: 1.

5 g of the polymer were pyrolyzed in a stream of ammonia at 1000 ° C. for 12 hours. 2.9 g of a black glossy amorphous powder were obtained, corresponding to a ceramic yield of 58%. Analytical data of the pyrolysis product:
Infrared Spectroscopy [cm ^-1 ]: 3400 (w); 950 (s); 530 (m). Powder diffractometry: amorphous.
Energy-dispersed X-ray analysis: Homogeneous element distribution at least up to the resolution limit of 0.5 µm, ratio Si: Zr = 1: 1

Example 4: Representation of a polyborosilazane with a Si / B ratio of 2: 1 Reaction equation:

Carrying out the experiment:

50 ml of NH _{3 were} added to a solution of 10 g (0.067 mol) of Si (NHCH ₃ ) ₄ in 400 ml of pentane at -78 ° C. with stirring. A solution of 4.83 g (0.0335 mol) of B (N (CH ₃ ) ₂ ) ₃ in 100 ml of pentane was added dropwise within 5 min. The reaction mixture was allowed to warm to room temperature over 12 h and stir for a further 4 h. The solvent was distilled off under reduced pressure. 10.3 g of white polyborosilazane were obtained. Analytical data of the polymer: infrared spectroscopy [cm ^-1 ]: 3440 (s); 2890, 2810 (s); 1600 (w); 1460 (m); 1360 (m); 1210 (m); 1090, 940 (ss); 800, 470 (m). Powder diffractometry: amorphous.

5 g of the polymer were pyrolyzed in a stream of ammonia at 1000 ° C. for 12 hours. 2.8 g of a white amorphous powder were obtained, corresponding to a ceramic yield of 56%. Analytical data of the pyrolysis product infrared spectroscopy [cm ^-1 ]: 3400 (w); 1350 (s); 1040 (ss); 460 (m). Powder diffractometry: amorphous.

Example 5: Representation of a polyalumozirconazane Reaction equation:

Carrying out the experiment:

NH _{3 was} introduced into a solution of 2.13 g (5.6 mmol) of Zr (NEt ₂ ) ₄ and 3.19 g (13.1 mmol) of Al (NEt ₂ ) ₃ in 100 ml of n-hexane at room temperature. A pale yellow precipitate formed, which was filtered off and freed of adhering solvent under reduced pressure. 1.55 g of pale yellow polyaluminozirconazane were obtained. Analytical data of the polymer:
Infrared Spectroscopy [cm ^-1 ]: 3270 (m); 2960, 2920, 2855 (s); 1535 (m); 1460 (m), 1380 (w); 1260 (s); 1095, 1020 (s); 800 (ss); , 600 (s, b). Powder diffractometry: amorphous.

1.5 g of the polymer were pyrolyzed in a stream of ammonia at 990 ° C. for 72 hours. 0.8 g of a white amorphous powder were obtained, corresponding to a ceramic yield of 53%. Analytical data of the pyrolysis product:
Infrared Spectroscopy [cm ^-1 ]: 3430 (m); 1635 (m); 1390 (w); 1150 (w); 710 (s, b).
Powder diffractometry: amorphous. Energy-dispersive X-ray analysis: Homogeneous element distribution at least up to the resolution limit of 0.5 µm, ratio Al: Zr ≈ 2: 1.

Example 6: Representation of a Polyalumotitanozirkonazans Reaction equation:

Carrying out the experiment:

A solution of 2.92 g (12 mmol) of Al (NEt ₂ ) ₃ , 2.02 g (6 mmol) of Ti (NEt ₂ ) ₄ and 0.76 g (2 mmol) of Zr (NEt ₂ ) ₄ in 100 ml of n-heptane was added at room temperature NH ₃ initiated. A brown-red precipitate formed, which was filtered off and freed of adhering solvent under reduced pressure. 2.15 g of brown-red polyalumotitanozirconazane were obtained. Analytical data of the polymer:
Infrared Spectroscopy [cm ^-1 ]: 3290 (m); 2960, 2920, 2855 (s); 2000 (w), 1550 (s, sh); 1465 (w), 1380 (w); 1260 (s); 1090, 1020 (s); 800 (s); 600 (s, vb). Powder diffractometry: amorphous.

2.1 g of the polymer were pyrolyzed in a stream of ammonia at 995 ° C. for 72 h. 1.4 g of a black amorphous powder were obtained, corresponding to a ceramic yield of 66%. Analytical data of the pyrolysis product:
Infrared Spectroscopy [cm ^-1 ]: 3435 (s); 1635 (m); 1400, 1385 (w); 740 (ss, sh).
Powder diffractometry: amorphous. Energy-dispersed X-ray analysis: Homogeneous element distribution at least up to the resolution limit of 0.5 µm.

Example 7: Representation of a polytitanovanado zirconazan Reaction equation:

Carrying out the experiment:

In a solution of 3.37 g (10 mmol) of Ti (NEt ₂ ) ₄ , 3.70 g (11 mmol) of V (NEt ₂ ) ₄ and 4.60 g (12 mmol) of Zr (NEt ₂ ) ₄ in 100 ml of tetrahydrofuran was methylamine at room temperature initiated. A black-green precipitate formed which was filtered off and freed of adhering solvent under reduced pressure. 3.71 g of black-green polytitanovanadozirkonazan were obtained. Analytical data of the polymer: infrared spectroscopy [cm ^-1 ]: 3255 (m); 2960 (s), 2855 (ss, sh), 2760 (s); 2100 (w), 1660 (w), 1575 (m), 1050, 1465, 1400, 1365 (m); 1260 (s); 1095, 1025 (s); 800 (s); , 600 (s, vb). Powder diffractometry: amorphous.

Example 8: Representation of a polytitanoborazane Reaction equation:

Carrying out the experiment:

NH _{3 was} introduced at 90 ° C. into a solution of 9.7 g (29 mmol) of Ti (NEt ₂ ) ₄ and 1.2 g (12 mmol) of B (NHCH ₃ ) ₃ in 100 ml of heptane. A black precipitate formed, which was filtered off and freed of adhering solvent under reduced pressure. 3.53 g of black polytitanoborazane were obtained. Analytical data of the polymer: infrared spectroscopy [cm ^-1 ]: 3290 (m); 2960, 2920, 2855 (s); 1640 (m); 1380 (w); 1100 (s, b); 600 (m, b). Powder diffractometry: amorphous.

3.5 g of the polymer were pyrolyzed at 1600 ° C. in a stream of nitrogen for 16 h. 1.75 g of a black powder were obtained, corresponding to a ceramic yield of 50%. Analytical data of the pyrolysis product: infrared spectroscopy [cm ^-1 ]: 3435 (s); 1650 (m); 1385 (m); 1150 (m, sh); 800 (w); 660, 600 (w). Powder diffractometry: largely amorphous; some weak, very broad peaks indicate a cubic unit cell with a = 4.26Å. Energy-dispersed X-ray analysis: No segregation observed, homogeneous element distribution at least up to the resolution limit of 0.5 µm.

Example 9: Representation of a polytitanoborazane Reaction equation:

Carrying out the experiment:

A mixture of 10.47 g (31 mmol) of Ti (NEt ₂ ) ₄ and 1.25 g (9 mmol) of B (N (CH ₃ ) ₂ ) ₃ was heated to 200 ° C. under an ammonia atmosphere. 2.9 g of brown-black polytitanoborazane were formed. Analytical data of the polymer: Infrared spectroscopy [cm ^-1 ]:
3290 (m); 2960, 2920, 2855 (s); 1640 (m); 1380 (w); 1100 (s, b); 600 (m, b). Powder diffractometry: amorphous.

2.9 g of the polymer were pyrolyzed in a stream of ammonia at 1000 ° C. for 12 hours. 2.0 g of a black powder were obtained, corresponding to a ceramic yield of 69%. Analytical data of the pyrolysis product: infrared spectroscopy [cm ^-1 ]: 3440 (s); 1635 (m); 1400, 1385 (m); 1100 (m, sh); 795 (w); 660, 600 (w), 470 (w). Powder diffractometry: amorphous. Energy-dispersed X-ray analysis: No segregation observed, homogeneous element distribution at least up to the resolution limit of 0.5 µm.

Example 10: Representation of a polytitanoborazane Reaction equation:

Carrying out the experiment:

A mixture of 6.8 g (20 mmol) of Ti (NEt ₂ ) ₄ and 5.8 g (40 mmol) of B (N (CH ₃ ) ₂ ) ₃ was heated to 200 ° C. under a methylamine atmosphere. 3.40 g of brown-black polytitanoborazane were formed. Analytical data of the polymer: Infrared spectroscopy [cm ^-1 ]:
3290 (m); 2960, 2920, 2855 (s); 1640 (m); 1380 (w); 1100 (s, b); 600 (m, b). Powder diffractometry: amorphous
3.40 g of the polymer was pyrolyzed at 800 ° C. for 72 hours under an argon atmosphere. 1.85 g of a black powder were obtained, corresponding to a ceramic yield of 55%. Analytical data of the pyrolysis product: Infrared spectroscopy [cm ^-1 ]: 3425 (s); 1635 (m); 1400, 1385 (s); 1100 (s, sh); 790 (w); 660, 600 (w), 470 (w).
Powder diffractometry: amorphous. Energy-dispersed X-ray analysis: No segregation observed, homogeneous element distribution at least up to the resolution limit of 0.5 µm.

Claims (8)

1. Polymeric multinary azanes which are built up of structural units of the general formula [E(NR¹R²)_a(NR³)_b/2], where E=B, Al, Ga, In, Si, Ge, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo or W and R¹, R², R³=H, C₁-C₆-alkyl, vinyl or phenyl, characterized in that at least two of the said elements E are present, with the exception of the combinations Si-B and Si-Al and each atom E is coordinated by from 3 to 6 nitrogen atoms, where 0≤a≤6, 1≤b≤6, 3≤(a+b)≤6 and a and b are integers.
2. Polymeric multinary azanes according to Claim 1, characterized in that the elements E are distributed homogeneously.
3. Polymeric multinary azanes according to Claim 1 or 2, characterized in that their chloride content is <100 ppm.
4. Polymeric multinary azanes according to Claim 3, characterized in that their chloride content is <20 ppm.
5. Process for preparing the polymeric multinary azanes according to one or more of Claims 1 to 4, characterized in that mixtures of element amides of the composition E(NR¹R²)_n, where 3≤n≤6, E=B, Al, Ga, In, Si, Ge, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo or W and R¹=H, C₁-C₆-alkyl, vinyl, phenyl, R²=C₁-C₆-alkyl, vinyl or phenyl, are polymerized in bulk or in an aprotic organic solvent with ammonia or primary amines.
6. Process for preparing the polymeric multinary azanes according to Claim 5, characterized in that the polymerization is carried out at temperatures between -80°C and 200°C, either in bulk or in an aprotic organic solvent which is a C₅-C₈-alkane, an acyclic or cyclic ether or an alkylaromatic, where the concentration of the amides being >0.01 M.
7. Use of the polymeric multinary azanes according to one or more of Claims 1 to 6 for preparing multinary nitrides or carbonitrides by pyrolysis at temperatures of from 400 to 2000°C in an atmosphere containing noble gas, N₂, NH₃ or primary amines.
8. Use of the polymeric multinary azanes according to one or more of Claims 1 to 6 for producing ceramic shaped bodies, films, fibres or coatings by pyrolysis at temperatures of from 400 to 2000°C in an atmosphere containing noble gas, N₂, NH₃ or primary amine.